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This paper not to be cited without prior reference to the authors

International Council for the Exploration of the Sea

C.M. 1984/K:20

Shellfish Committee

THE SQUID TODARODES SAGITTATUS (LAMARCK)

INVESTIGATIONS IN NORWEGIAN COASTAL AND BANK WATERS, JULY 1983-JANUARY 1984, AND WEST OF THE BRITISH ISLES,

MARCH-APRIL 1984

ABSTRACT

by

Kristian Fredrik Wiborg and

Inger Marie Beck

Institute of Marine Research B6x 1870, N-5011 Bergen, Norway

During the second half of 1983 Todarodes sagittatus invaded the coast of Norway to the same extent as in 1982. Materials for investigation were obtained from research cruises near Shetland in July, on the Viking Bank in August, in coastal and bank waters of western and northern Norway from August 1983 to January 1984, and west of the British Isles in March-April 1984.

In August two size groups, dorsal mantle length (DML) 20-31 cm and 34-47 cm, were present on the Viking Bank and off the coast of Norway. In July-October the squid in fjords in western Norway measured 20-28 cm; in November the mean length was 35 cm; in Jariuary 36.6 cm. In March-April two size groups, 20-29 cm and 31-44 cm were present west of the British Isles.

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The stomach contents were mainly fish; pearlside, blue whiting, saithe, redfish and a few others. Euphausiids, copepods and sp. were sometimes important as food, while squid seldom surpass 20% in frequency

Liver weights were low near Bergen, on an average 4-8! of total weight, in other areas 10-11%.

Males were scarce or absent in jig samples from .coastal areas, in trawl samples from oceanic areas, ^31~63%.

In August, males 34 40 cm were all mature or maturing, females 37-47 cm in maturing stages 2-3.

Age determinations based on counts of primary growth rings in the statoliths indicated average ages of 8-10 months.

The main spawning season seems to be November-January. Squid caught in January had probably been hatched in March-April, those taken in March-April, - in May-August.

The relationship statolith length/ dorsal mantle length (TLS/

DML) was calculated for males and females. At the same DML, males had larger TLS than the females, the difference decreas- ing with increasing DML. Tagging of 452 squid resulted in two recaptures near the tagging place one month after tagging.

Attempts to keep

I·

sagittatus in aquarium were unsuccessful.

The commercial fishery yielded 19 ⁰⁰⁰ m tons.

INTRODUCTION

During the second half of 1983 the invasion of

I·

sagittatus to the coastal areas of Norway was of nearly the same extent as in the previous year. Single squid appeared near Shetland in July. In fjords in western Norway the squid were very abundant from· the beginning of August to the end of November. The

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Table 1. Dor.-sal mantle length (DML) of!:_ EaJ~iJ:t~, July 1983-April 1984. n-number, SD•._1t-rndard deviation. For location, see Figs 1,2.

Area

Date

.em

w

n

21 23 14 lS 16 1.1 28 Z9 :30

n

J!

n

34 ) j

l6

17

1'8 3t 40 41 42 43 44 45

4l).

47 n DML at SD

Q

~

ISLE

2

2.

2

' 11

1 .. 6

VIKING BANK

Aug.2,4,18

c!

n

1

1 1

1

1 8 2 4 3 1 3

~ n

2 3 3 4 1 2 1

1

2

1 3 3 1

4 17 23.4 25.8

2.3 2.6

n lJ 43.0 1,9 3.1

COASTAL ~uGANDET BLOMVAG ALESUND -BANK

Aug.4,18

c! ~

n n

1

2

1- 1

Aug.3

c! ~

n %

1.9 3.9 8.5 4 13.7 1 20.9 14.4 1 21.6 10.5 3.3 1.3

Aug.24

c! ~

n %

Sep.5-8

c! ~

n n

1 1 1 5.6 4 1 7.0 5 1 8.4

2 3 2 6 1 1 2 3 1 14.1

7.1 21.1 1 15.5 12.7 7.1

1.4

2- 3 6 153 4 11 ll 21

24.9 25.9 24.1 26.7 22.4 26.8 1.1 1.9 2.6 2.4 1.0 2.4

BERGEN COAS!a.u BANKS

BERGEN BERGEN HE~0Y- SYLTE- WEST OF HOLMEN FJORD BRITiSH ISLES

Sep.15 Oct.4-11 Oct.6 Oct.12 Nov.8 Jan.25 6

c! ~

n %

1 .. 0 1 2,..6 2 3.,2

d' n

11 .. 4 1

4 u .. s ¹ u,.a

1 13.3

e.l

~.1 1

t.s

t .. o

o .. s

196 4

!5.7 15.9 2.0 2~1

~ n

1

1 1 1 1

~ n

1 l 1 7 4 2

c!

n

2 1

3

~

%

1.0 3.0 4.5 18.0 22.0 19.5 11.5

~

%

1.2 3.7 10.5 4.9 4.5 3.7 0 . .5 6.2 1..5 16.0 3.5 9.9 0.5 8.6

200·

7.4 12.3 14.8 6.2 4.9

Bl 24.7 2S.O 34.9

o. 2 1 .. 2 .4.5

~ n

1 2 4

7

!\i6a6 c!

n

1 1

3 5 2 3

1

~ n

2 4 4 9 4 5 2

1

1 1

1

1 1

15 31

24.1 24.5 1.7 1.8

1 5

l7.4 6.1

w

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74°

73° ¹X

2 • 3 +

4 6

720 ₅_Ill

64 71°

70°

69°

68°

67° 6

66°

•

1000 M

'65°

•

Fig. 1. Localities for sampling of!· sagittatus, July 1983-January 1984. 1) July, 2) August, 3) September, 4) November, 5) January.

materials from 1983 have been dealt with (WIBORG and BECK 1984).

MATERIALS AND METHODS

Squid were caught during cruises in July-October 1983 and March-April 1984, and bought from commercial catches in August- January (Table 1, Fig. 1,2). In open waters the squid were

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0

62

54"

I I

~-·-'. .

/ PORCUPINE

BANK

5

FAROES

~~~

~

0

' '

'·ao,r: -..~

~~

/ ~&

, , 'C;)•"(j

/,'~~~~DES~ r~

: C)

if'_ f"

'. q- ~

I

10~0 M

I I

)

If{ ..

_,.{f\

(]

52°4-~--~--~~~~--~-+~~~--~--~~--~~--~--+

15°

Fig. 2. Stations for trawl catches of !· sagittatus, March-April 1984. 1) March 9-18. 2) March 29-April 6.

taken in pe lagic or bottom trawl, in the fjords with jigs.

Some measurements are from squid which were tagged and re- leased. Dorsal mantle lengths were measured to the nearest half cm below, total weight and liver weight to the nearest 5 g. Stomach contents were studied under a stereoscopic microscope. Statoliths were taken from 10-50 squid in each sample and kept in 96% ethyl-alcohol until examination. The lengths

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of the statoliths were measured under microscope .to the nearest 1/100 mm. The statoliths were prepared, and primary growth rings counted as described by ROSENBERG, WIBORG and BECK (1980). Maturity stages were determined after WIBORG et al.

(1982). In two localities, 452 squid were tagged with anchor tags and releasedo

RESULTS AND DISCUSSION Dorsal mantle length

In July the squid near Shetland measured 20-25 cm (Table 1).

In August two size groups, 20-31 cm, and 34-47 cm, were observed on the Viking bank. The same groups appeared off the Norwegian Shelf (Egga) between 66°N and 73°N. At the coast of western Norway only small squid were taken, mean DML of females, 25-27 cm. In the fjords the squid remained small

throughout October; near the continental slope larger squid, DML 32-36 cm, were taken. At the beginning of November the mean length of squid at the west coast was 35 cm, in January 36.6 cm. In March-April two size groups, 20-29 cm and 31-44 cm, were observed west of the British Isles.

Stomach contents

The frequency of vari'ous food organisms in the stomachs of T.

sagittatus in samples taken during July 1983-March 1984 is shown in Table 2. Empty stomachs are excluded.

Fish were nearly always dominating. Euphausiids, pelagic shrimps and copepods were sometimes very common, while squid varied between 7 and 33%.

The species of fish identified at various localities are listed below, frequency in the order mentioned:

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Shetland, Julv~

Vikjng Rank, August:

BulAndet, August:

7

Hlue 'VIJhj ti ng

Blue whiti.~g, neRrlside, silver smel~,

silverv pout

Pe.1rl side, b 1 ue \h?hi ting, s~d the, f.'Rnd eeJ., rcdfish

BlomvAg, August: Pearlside, blue whiting, s;:~ithe

Alesund, September: PeAr] ~d.de, s::d the~ blue \vhiting, herring

F.ergen, September: Pearlside, blue whit5ng~ herring, redfi.sh

Coastc:ll banks, October: Blue \~7hiting, redfish, pearlside

Hermyholmen, November: PearJside, lantern fish, bJue 1<1hitin~,

Norway pout Syltefjord, January:

We~t of the British Isles, March~

Herring, pearlside

Blue whiting, Argvropelecus silvery pout, pear]side.

sn.,

Blue whiting dominated in squid from trawl samples, while pearlside was most important in those caught with iigs.

Table 2. Frequency (%) of food organisms in stomach contents of T. sagittatus, Ju1y 1983 -

March 1984. n-number.

Locality Month n Fish Squid Euphau- Shrimps Amphi- Cope- Nerei.s Chaeto-

siids pods pods gnaths

Shetland July 16 100.0 12.5 37.5

Viking Bank August 45 80.0 11.1 75.5 2.2

Bulanclet August 29 89.7 13.R 13.8 2.2 17.2 58.6

Blomvag August 30 73.3 6.7 30.0 36.7 3.3 3.3

Alesund Sept. 21 71.4 19.1 23.8 28.6 14.3 23.8

Bergen Sept. 21 75.3 33.3 95.3 9.5 9.5

Bergen Sept. 12 75.0 16.7

Coastal banks October 15 46.7 40.0 6. 7

Her<t>yho lmen November 31 87.1 1:· 83.9 38.7 12.9 6.5

Syltefjord January 7 71.0 43.0 14.0

hlest of

"

Brit. Isles March 38 92.1 5.3 29.0 .5.3

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Liver percentage

Variations and mean percentage of weight of liver in relation to total weight are shown in Table 3. The range of variation is very great, 1.9-17.0%. The mean values were below 4% near Bergen in October, probably reflecting poor feeding conditions.

In other areas the mean figures varied from 7 to 11%. On the Viking Bank, larger squid had somewhat higher percentage than the smaller ones, but the difference is not significant.

Table 3. Weight of liver in % of total weight of !· sagittatus, July 1983- March 1984. n-number, SD-standard deviation.

Locality tvlonth n Variation Mean SD

Shetland July 16 5.6-13.0 9.6 1.8

Viking Bank August

DML 35-48 cm 33 6.6-17.0 11.3 2.8

DML 22-35 cm 16 5.6-12.2 10.4 2.8

Blomvag August 30 3.3-14.4 8.1 2.4

Bergen September 23 1.9- 8.4 4.8 1.7

Bergen October 21 2.8- 6.8 3.9 0.9

Coastal banks October 9 4.3-10.4 7.3 3.2

Her~t>yholmen November 31 4.5-14.6 10.1 3.2

Syltefjord January 7 7.8-12.7 10.3 1,9

West of British Isles March 46 2.7- 9.5 5.8 1.4

Sex ratio

As shown in Table 1, males were most often scarce or absent in the samples, especially in those taken with jigs. During a fishing experiment near Alesund it was observed that the males kept near the surface, under the bottom of the vessel, while the females stayed at deeper levels. In trawl samples taken on the Viking Bank and Porcupine Bank, males constituted 31-63%.

Maturation

Maturity stages were determined after WIBORG et al. (1982). In August, males with DML below 28 cm and females with DML below 31 ern, were immature (Stage 1). Males, DML 36-40 cm, were maturing or mature, 8 in Stage 2 and 14 in Stage 3, the latter

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9

with spermatophores well developed. Females, .DML 37-47 cm, were ly (3)~ ly Stage 2(6) and Stage 3(3).

The sence of mature males does not indicate a forthcoming spawning. In Todarodes , a squid nearly related to

!·

-"""'----, mature males are relatively common, and mating may

take place long time before spawning, while mature females are rare (SASAKI 1921).

Primary growth rings in the statoliths have been counted, following the method of ROSENBERGP WIBORG and BECK (1980). The results from the present material are shown in Table 4. Assum- ing the growth rings to represent daily growth, the squid had average ages of 225-295 days (7~-10 months). In August, large squid on the Viking Bank (DML 34-48 cm) were 34 days older than those with DML 23-31 cm. As shown in Table 1, the large males had an average DML about 6 cm less than the females (36.9 cm and 43.0 cm). When the age distribution was split up the difference in mean age was not significant (19 males: 286.16±

28.00 rings, 13 females: 280.08±23.32 rings).

Squid, caught in August, seems to have been hatched in the period October-January, with maximum in November-December, those from September-November were hatched in December- February, and those from January, in March-April. T.

sagittatus, caught west of the British Isles in March-April, had been hatched during May- September, most of them in June.

The results agree relatively well with those obtained for the same areas and periods during the preceeding year (WIBORG,

GJ0S~TER and BECK 1983).

Most of the squid fished commercially in Norway is taken during the period August-November. These squid have mainly been hatched during December-January, 8-11 months earlier.

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Locality Date Sep. Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug. Sep. n MV SD

Shetland July 23 5 7 1 13 230.88 18.54

Coast of Norway Aug. 4,18 2 1 1 4 267.00 31.92

Viking bank Aug. 2,18

34-48 cm 9 10 11 2 32 283.68 25.97

23-31 cm 3 4 9 16 249.06 19.72

Bulandet Aug. 3 2 22 4 28 224.61 14.77

Blomvag Aug. 24 1 18 9 28 245.11 13.38

Xlesund Sep. 6, 7 9 18 2 29 238.69 14.92

Bergen Sep. 15 6 9 4 19 243.84 16.70

Bergen Oct. 6 10 10 1 21 245.52 14.45

Coastal banks Oct. 4-11 6 4 10 274.00 17.70

Her(t>yholmen Nov. 8 3 20 8 31 295.29 14.45

Syltefjord Jan. 25 2 4 6 290.00 14.10

W. of Br. Isles Mar.9-Apr.6 10 21 10 3 1 45 276.22 27.92

1--' ,o

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Relationship: statolith length/dorsal mantle length

The relationship between greatest length of the statoliths (TLS) in mm, and dorsal mantle length (DML) in cm was studied.

for males and females ofT. sagittatus (Fig. 3). The following equations were found:

Males:

=

0.4938 DML0·41

,

_r2

=

Females:

TLS

=

0.4259 DML0 · 45 , r2

=

0.75, n = 79 0.76, n

=

303

:l:

~

:r:

1- (!)

z

~ :r:

1- --' 0 1-~ 1- tll

2.50

2.40

2.3

2.20

2.10

2.

1.90

1.80

1.70 ,../' 1.60

1.50

..

X

>)(X X o ,

X e e,.. ... "'

e X ctX e ct ,., ...

@ • _..."''

•• ••J>'"'"

X G .... • u 1$> e

.,.r x • • •

a e e ~... e

..

^~" ^~/-

•

....

G X )( ^,~Ilia ,ree)J;e

...

: )4&8 ./.•,;". : 0 • . .

.. x,vx• ex x eei$>X

o X o " !10' X e e e ,W)41to e X e e X X,.., et e

X

.

o ^....^...^,.,..,

.

eX e,....ee a

llx • .!"*••

)( )( /~;. 2 • • :. :.

. .... • " • , . . • • • • • ell X X,..' ct G o e )( • •

,X/:~ oo -~ ... "

x'/ X

/ .... ^"/'

20 25 30 35 40

DORSAL MANTLE LENGTH CM

45 50

Fig. 3. Relationship: Total statolith length(TLS)/dorsal mantle length(DML) in !· sagittatus in materials from 1983. Crosses and hatched curve: males, dots and drawn curve, females. Equations: see text.

At the same DML males have longer stat~liths than the females, but the relationships are not significantly different. The curves approach each other at increasing DML. LIPINSKI (1981) did not find any difference in the relationship for males and females of Illex illecebro

I

. I

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In 1983, 452 squid were tagged with anchor tags, 69 near Alesund in September, and the remainder near Bergen in Sep-

tember and October. Two squid were recaptured near the tagging place at Alesund, respectively 24 and 34 days after tagging.

Survival of squid in aquarium

Experiments with maintaining squid in aquarium have been made by several scientists, especially with

!·

pacificus. FLORES, IGARASHI and MIKAMI (1977) succeeded 'in keeping

!·

pacificus alive for 50 days.

During the autumn of 1983 we tried three times to maintain T.

sagittatus in aquarium, but the attempts were all unsuccessful.

The squid were fished near Bergen with hand line, placed singly in tubs with 20 1 of seawater and transported to the Institute.

The seawater was renewed once during the transport which lasted for ^~hour. The squid were placed 15-30 together in a rectan- gular aquarium of concrete of 40 m3

capacity. They swam frantically around, bumping against the walls of the aquarium, and also attacking each other. During the two first experiments all were dead after 6-7 hours. In the third experiment,

the walls of the aquarium had been covered with sheets of black plastic, but the squid panicked, bumped against the bottom, and also succeeded in swimming beneath the cover. Only 2 squid survived for 24 hours. The dark cover may have contributed to the panic, because the squid did not see the walls.

In future experiments the squid should be kept singly in small tanks, or perhaps in large circular tanks or "raceway systems"

(0' DOR, DURWARD and BALCH 1977, MATSUMOTO and SHIMADA ^1980, HANLON, HIXON and HULET 1983);

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Fishery for T. sagittatus

In 1983 the Norwegian shery yielded 19 000 tons of squid,

·mainly in August=November, with maximum quantities in September and October.

Acknowledgement

We wish to thank Karsten Hansen and Berit Endresen for assi- stance during cruises, working with th~ material, and drawing of figures. Also many thanks to Wenche Meidell for typing the manuscript.

REFERENCES

HANLON, R. T., HIXON, R. F. and HULET, W. H. 1983. Survival,

g~owth and behavior of the. loliginid squids Loligo plei, LoliSC? pealei and Lolliguncula brevis (Mol- lusca, Cephalopoda) in closed sea water systems.

Biol Bull 16 : 637-685.

LIPINSKI, M. 1981. Statoliths as a possible tool for squid age determination. Bull. L'Acad. Pol. Sci. Ser. sci.

bio1., 28(10-11): 569-582.

MATSUMOTO, G. and SHIMADA, J. 1980. Further improvement upon maintenance of adult squid (Doryteuthis bleekeri in a small circular and closed-system aquarium tank.

Biol Bull 1 9: 319-324.

O'DOR, R.K., DURWARD, R.D. and BALCH, N. 1977. Maintenance and maturation of squid illecebrosus) in a 15 m circular pool. ---~----Biol : 322-335.

ROSENBERG, AoA., WIBORG, K.F. and BECK, I.M. 1980. Growth of Todarodes sagittatus(Lamarck) (Cephalopoda, Ommastre- phidae) from the northeast Atlantic, based on counts of statolith growth rings. Sarsia 66: 53-57.

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SASAKI, M. 1921. On the life history of an economic cuttlefish of Japan, Ommastrephes sloani pacificus.

Wagner Free Inst., 9(2): 1-25.

Trans.

WIBORG, K.F. and BECK, I.M. 1984. Akkar Todarodes sagittatus (Lamarck)). Unders<t>kelser i norske kyst- og bank- farvann juli-november 1983. Fisken Hav., 1984(2):

13-23.

WIBORG, K.F., GJ0SJETER, J. and BECK, I.M. 1983. The squid Todarodes sagittatus(Lamarck). Distribution and biology in northern waters August 1982-June 1983.

Coun. Meet. int. Coun. Explor. Sea, 1983(K:7): 1-15.

(Mimeo).

WIBORG, K. F. , GJ0SJETER, J. , BECK, I. M. and FOSSUM, P. 1982.

The squid Todarodes sagittatus(Lamarck). Distri- bution and biology in northern waters August 1981- April 1982. Coun. Meet. int. Coun. Explor. Sea, 1982 (K: 30): 1-17. (Mimeo).